The International Classification of Diseases for Oncology (ICD-O) is a domain specific extension of the International Classification of Diseases (ICD) for Tumour diseases. This classification is widely used by the National Cancer Registration and Analysis Service for coding the site (topography) and the histology (morphology) of neoplasms, usually obtained from a pathology report. The International Classification of Diseases for Oncology (ICD-O) is published by the World Health Organisation.

For further information on the International Classification of Diseases for Oncology (ICD-O), see the World Health Organisation website at: International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3).